It is known to provide corrosion-resistant steels of the following composition:
up to 0.1% by weight carbon PA1 up to 1.0% by weight silicon PA1 up to 2.0% by weight manganese PA1 up to 0.045% by weight phosphorus PA1 up to 0.030% by weight sulfur PA1 26.0% to 28.0% by weight chromium PA1 1.3% to 2.0% by weight molybdenum PA1 4.0% to 5.0% by weight nickel, balance iron and unavoidable impurities. PA1 up to 0.1% by weight carbon, PA1 up to 1.0% by weight silicon, PA1 4.0% to 6.0% by weight manganese, PA1 22.0% to 28.0% by weight chromium, PA1 3.5% to 5.5% by weight nickel, PA1 1.0% to 3.0% by weight molybdenum, PA1 0.35% to 0.6% by weight nitrogen, PA1 balance iron and unavoidable impurities. PA1 up to 0.1% by weight carbon, PA1 up to 1.0% by weight silicon, PA1 4.5% to 5% by weight manganese, PA1 25.0% to 27.5% by weight chromium, PA1 3.5% to 5.0% by weight nickel, PA1 1.3% to 2.5% by weight molybdenum, PA1 0.35% to 0.45% by weight nitrogen, PA1 balance iron and unavoidable impurities.
This austenitic-chromium-nickel steel has been found to have low corrosion rates and to be suitable, in many cases, for mechanical working. It has been referred to as No. 1.4460 steel and is analogous to Swedish steel of the Swedish industrial standard SIS 2324 which contains nitrogen in amounts up to 0.2% by weight.
Such steels, however, have not proved to be completely satisfactory in strength and in notch impact strength or tenacity for the fabrication of corrosion resistant forgings by impact forging processes. When attempts are made to raise the nitrogen content up to 0.4% by weight, the mechanical properties can be improved at least in part although the forging properties deteriorate, as evidenced by a strong tendency to the formation of cracks during forging.